/*
* Copyright (C) 2007 Oracle.  All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H

#define LIST_POISON1  ((struct list_head *) 0x00100100)
#define LIST_POISON2  ((struct list_head *) 0x00200200)

/*
 * Simple doubly linked list implementation.
 *
 * Some of the internal functions ("__xxx") are useful when
 * manipulating whole lists rather than single entries, as
 * sometimes we already know the next/prev entries and we can
 * generate better code by using them directly rather than
 * using the generic single-entry routines.
 */

struct list_head {
        struct list_head *next, *prev;
};

#define LIST_HEAD_INIT(name) { &(name), &(name) }

#define LIST_HEAD(name) \
        struct list_head name = LIST_HEAD_INIT(name)

static inline void INIT_LIST_HEAD(struct list_head *list)
{
        list->next = list;
        list->prev = list;
}

/*
 * Insert a new entry between two known consecutive entries.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
#ifndef CONFIG_DEBUG_LIST
static inline void __list_add(struct list_head *xnew,
                              struct list_head *prev,
                              struct list_head *next)
{
        next->prev = xnew;
        xnew->next = next;
        xnew->prev = prev;
        prev->next = xnew;
}
#else
extern void __list_add(struct list_head *xnew,
                              struct list_head *prev,
                              struct list_head *next);
#endif

/**
 * list_add - add a new entry
 * @new: new entry to be added
 * @head: list head to add it after
 *
 * Insert a new entry after the specified head.
 * This is good for implementing stacks.
 */
#ifndef CONFIG_DEBUG_LIST
static inline void list_add(struct list_head *xnew, struct list_head *head)
{
        __list_add(xnew, head, head->next);
}
#else
extern void list_add(struct list_head *xnew, struct list_head *head);
#endif


/**
 * list_add_tail - add a new entry
 * @new: new entry to be added
 * @head: list head to add it before
 *
 * Insert a new entry before the specified head.
 * This is useful for implementing queues.
 */
static inline void list_add_tail(struct list_head *xnew, struct list_head *head)
{
         __list_add(xnew, head->prev, head);
 }

 /*
  * Delete a list entry by making the prev/next entries
  * point to each other.
  *
  * This is only for internal list manipulation where we know
  * the prev/next entries already!
  */
 static inline void __list_del(struct list_head * prev, struct list_head * next)
 {
         next->prev = prev;
         prev->next = next;
 }

 /**
  * list_del - deletes entry from list.
  * @entry: the element to delete from the list.
  * Note: list_empty on entry does not return true after this, the entry is
  * in an undefined state.
  */
 #ifndef CONFIG_DEBUG_LIST
 static inline void list_del(struct list_head *entry)
 {
         __list_del(entry->prev, entry->next);
         entry->next = LIST_POISON1;
         entry->prev = LIST_POISON2;
 }
 #else
 extern void list_del(struct list_head *entry);
 #endif

 /**
  * list_replace - replace old entry by new one
  * @old : the element to be replaced
  * @new : the new element to insert
  * Note: if 'old' was empty, it will be overwritten.
  */
 static inline void list_replace(struct list_head *old,
                                 struct list_head *xnew)
 {
         xnew->next = old->next;
         xnew->next->prev = xnew;
         xnew->prev = old->prev;
         xnew->prev->next = xnew;
 }

 static inline void list_replace_init(struct list_head *old,
                                         struct list_head *xnew)
 {
         list_replace(old, xnew);
         INIT_LIST_HEAD(old);
 }
 /**
  * list_del_init - deletes entry from list and reinitialize it.
  * @entry: the element to delete from the list.
  */
 static inline void list_del_init(struct list_head *entry)
 {
         __list_del(entry->prev, entry->next);
         INIT_LIST_HEAD(entry);
 }

 /**
  * list_move - delete from one list and add as another's head
  * @list: the entry to move
  * @head: the head that will precede our entry
  */
 static inline void list_move(struct list_head *list, struct list_head *head)
 {
         __list_del(list->prev, list->next);
         list_add(list, head);
 }

 /**
  * list_move_tail - delete from one list and add as another's tail
  * @list: the entry to move
  * @head: the head that will follow our entry
  */
 static inline void list_move_tail(struct list_head *list,
                                   struct list_head *head)
 {
         __list_del(list->prev, list->next);
         list_add_tail(list, head);
 }

 /**
  * list_is_last - tests whether @list is the last entry in list @head
  * @list: the entry to test
  * @head: the head of the list
  */
 static inline int list_is_last(const struct list_head *list,
                                 const struct list_head *head)
 {
         return list->next == head;
 }

 /**
  * list_empty - tests whether a list is empty
  * @head: the list to test.
  */
 static inline int list_empty(const struct list_head *head)
 {
         return head->next == head;
 }

 /**
  * list_empty_careful - tests whether a list is empty and not being modified
  * @head: the list to test
  *
  * Description:
  * tests whether a list is empty _and_ checks that no other CPU might be
  * in the process of modifying either member (next or prev)
  *
  * NOTE: using list_empty_careful() without synchronization
  * can only be safe if the only activity that can happen
  * to the list entry is list_del_init(). Eg. it cannot be used
  * if another CPU could re-list_add() it.
  */
 static inline int list_empty_careful(const struct list_head *head)
 {
         struct list_head *next = head->next;
         return (next == head) && (next == head->prev);
 }

 static inline void __list_splice(struct list_head *list,
                                  struct list_head *head)
 {
         struct list_head *first = list->next;
         struct list_head *last = list->prev;
         struct list_head *at = head->next;

         first->prev = head;
         head->next = first;

         last->next = at;
         at->prev = last;
 }

 /**
  * list_splice - join two lists
  * @list: the new list to add.
  * @head: the place to add it in the first list.
  */
 static inline void list_splice(struct list_head *list, struct list_head *head)
 {
         if (!list_empty(list))
                 __list_splice(list, head);
 }

 /**
  * list_splice_init - join two lists and reinitialise the emptied list.
  * @list: the new list to add.
  * @head: the place to add it in the first list.
  *
  * The list at @list is reinitialised
  */
 static inline void list_splice_init(struct list_head *list,
                                     struct list_head *head)
 {
         if (!list_empty(list)) {
                 __list_splice(list, head);
                 INIT_LIST_HEAD(list);
         }
 }

 /**
  * list_entry - get the struct for this entry
  * @ptr:        the &struct list_head pointer.
  * @type:       the type of the struct this is embedded in.
  * @member:     the name of the list_struct within the struct.
  */
 #define list_entry(ptr, type, member) \
         container_of(ptr, type, member)

 /**
  * list_for_each        -       iterate over a list
  * @pos:        the &struct list_head to use as a loop cursor.
  * @head:       the head for your list.
  */
 #define list_for_each(pos, head) \
         for (pos = (head)->next; pos != (head); \
                 pos = pos->next)

 /**
  * __list_for_each      -       iterate over a list
  * @pos:        the &struct list_head to use as a loop cursor.
  * @head:       the head for your list.
  *
  * This variant differs from list_for_each() in that it's the
  * simplest possible list iteration code, no prefetching is done.
  * Use this for code that knows the list to be very short (empty
  * or 1 entry) most of the time.
  */
 #define __list_for_each(pos, head) \
         for (pos = (head)->next; pos != (head); pos = pos->next)

 /**
  * list_for_each_prev   -       iterate over a list backwards
  * @pos:        the &struct list_head to use as a loop cursor.
  * @head:       the head for your list.
  */
 #define list_for_each_prev(pos, head) \
         for (pos = (head)->prev; pos != (head); \
                 pos = pos->prev)

 /**
  * list_for_each_safe - iterate over a list safe against removal of list entry
  * @pos:        the &struct list_head to use as a loop cursor.
  * @n:          another &struct list_head to use as temporary storage
  * @head:       the head for your list.
  */
 #define list_for_each_safe(pos, n, head) \
         for (pos = (head)->next, n = pos->next; pos != (head); \
                 pos = n, n = pos->next)

 /**
  * list_for_each_entry  -       iterate over list of given type
  * @pos:        the type * to use as a loop cursor.
  * @head:       the head for your list.
  * @member:     the name of the list_struct within the struct.
  */
 #define list_for_each_entry(pos, head, member)                          \
         for (pos = list_entry((head)->next, typeof(*pos), member);      \
              &pos->member != (head);    \
              pos = list_entry(pos->member.next, typeof(*pos), member))

 /**
  * list_for_each_entry_reverse - iterate backwards over list of given type.
  * @pos:        the type * to use as a loop cursor.
  * @head:       the head for your list.
  * @member:     the name of the list_struct within the struct.
  */
 #define list_for_each_entry_reverse(pos, head, member)                  \
         for (pos = list_entry((head)->prev, typeof(*pos), member);      \
              &pos->member != (head);    \
              pos = list_entry(pos->member.prev, typeof(*pos), member))

 /**
  * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue
  * @pos:        the type * to use as a start point
  * @head:       the head of the list
  * @member:     the name of the list_struct within the struct.
  *
  * Prepares a pos entry for use as a start point in list_for_each_entry_continue.
  */
 #define list_prepare_entry(pos, head, member) \
         ((pos) ? : list_entry(head, typeof(*pos), member))

 /**
  * list_for_each_entry_continue - continue iteration over list of given type
  * @pos:        the type * to use as a loop cursor.
  * @head:       the head for your list.
  * @member:     the name of the list_struct within the struct.
  *
  * Continue to iterate over list of given type, continuing after
  * the current position.
  */
 #define list_for_each_entry_continue(pos, head, member)                 \
         for (pos = list_entry(pos->member.next, typeof(*pos), member);  \
              &pos->member != (head);    \
              pos = list_entry(pos->member.next, typeof(*pos), member))

 /**
  * list_for_each_entry_from - iterate over list of given type from the current point
  * @pos:        the type * to use as a loop cursor.
  * @head:       the head for your list.
  * @member:     the name of the list_struct within the struct.
  *
  * Iterate over list of given type, continuing from current position.
  */
 #define list_for_each_entry_from(pos, head, member)                     \
         for (; &pos->member != (head);  \
              pos = list_entry(pos->member.next, typeof(*pos), member))

 /**
  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
  * @pos:        the type * to use as a loop cursor.
  * @n:          another type * to use as temporary storage
  * @head:       the head for your list.
  * @member:     the name of the list_struct within the struct.
  */
 #define list_for_each_entry_safe(pos, n, head, member)                  \
         for (pos = list_entry((head)->next, typeof(*pos), member),      \
                 n = list_entry(pos->member.next, typeof(*pos), member); \
              &pos->member != (head);                                    \
              pos = n, n = list_entry(n->member.next, typeof(*n), member))

 /**
  * list_for_each_entry_safe_continue
  * @pos:        the type * to use as a loop cursor.
  * @n:          another type * to use as temporary storage
  * @head:       the head for your list.
  * @member:     the name of the list_struct within the struct.
  *
  * Iterate over list of given type, continuing after current point,
  * safe against removal of list entry.
  */
 #define list_for_each_entry_safe_continue(pos, n, head, member)                 \
         for (pos = list_entry(pos->member.next, typeof(*pos), member),          \
                 n = list_entry(pos->member.next, typeof(*pos), member);         \
              &pos->member != (head);                                            \
              pos = n, n = list_entry(n->member.next, typeof(*n), member))

 /**
  * list_for_each_entry_safe_from
  * @pos:        the type * to use as a loop cursor.
  * @n:          another type * to use as temporary storage
  * @head:       the head for your list.
  * @member:     the name of the list_struct within the struct.
  *
  * Iterate over list of given type from current point, safe against
  * removal of list entry.
  */
 #define list_for_each_entry_safe_from(pos, n, head, member)                     \
         for (n = list_entry(pos->member.next, typeof(*pos), member);            \
              &pos->member != (head);                                            \
              pos = n, n = list_entry(n->member.next, typeof(*n), member))

 /**
  * list_for_each_entry_safe_reverse
  * @pos:        the type * to use as a loop cursor.
  * @n:          another type * to use as temporary storage
  * @head:       the head for your list.
  * @member:     the name of the list_struct within the struct.
  *
  * Iterate backwards over list of given type, safe against removal
  * of list entry.
  */
 #define list_for_each_entry_safe_reverse(pos, n, head, member)          \
         for (pos = list_entry((head)->prev, typeof(*pos), member),      \
                 n = list_entry(pos->member.prev, typeof(*pos), member); \
              &pos->member != (head);                                    \
              pos = n, n = list_entry(n->member.prev, typeof(*n), member))

 #endif
